JPH11285649A - Roller mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely restrain the vibration of a pulverizing roller with respect to a roller mill in which pulverizing load is given to the pulverizing roller by hydraulic force of a hydraulic cylinder. SOLUTION: A damper device 34 constituting of a throttle valve 35, an accumulator 36, and the like is connected to a hydraulic cylinder 15 to which pressurizing oil is fed on the rod 3 side thereof. During roller mill operation, vibration energy of the pressurizing oil is absorbed by the damper device 34 to restrain the vibration of a pulverizing roller. To two air vent parts 38, 39 provided on the rod side of the hydraulic cylinder, an gas removing device 42 is connected through valves 40, 41. To piping for the gas removing device 42, the damper device 34 is connected through valves 46 and 47. In the case air is mixed in the pressurizing oil in the hydraulic cylinder, by switching the valves, the gas removing device 42 is made to communicate with the hydraulic cylinder or the damper device 34 to remove the air mixed in the hydraulic oil on the rod side and the damper device 34 side of the hydraulic cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller mill for pulverizing a raw material such as coal by a rotating rotary table and a grinding roller rotating in conjunction with the rotary table on a groove formed on an outer peripheral side of the rotary table. In particular, the present invention relates to a vibration suppressing mechanism for suppressing vibration of a crushing roller.

[0002]

2. Description of the Related Art In coal-fired boilers, low-pollution combustion (low NO
x, low ash unburned matter) and wide area load operation, and accordingly, pulverized coal machines (mills) are also required to have high pulverizing performance and reliability. Recently, as one type of mill for finely pulverizing lump such as coal, cement raw material or new raw material, a vertical roller mill which pulverizes with a rotating table and a plurality of rollers has been widely used.

FIG. 5 is a cross-sectional view showing a schematic configuration of a general roller mill. This type of roller mill has a cylindrical housing 1 and a substantially circularly-shaped rotary table 2 disposed under the housing 1. And a plurality of crushing rollers 3 arranged at equal positions in the circumferential direction of the rotary table 2. The turntable 2 is driven by a motor (not shown) to rotate at a low speed via a speed reducer 18, and a groove-shaped crushing race 6 is formed on an upper surface of an outer peripheral portion thereof. Each grinding roller 3 has a shaft extending behind the grinding roller 3 rotatably supported by a roller bracket 11, and the roller bracket 11 is connected to a pressure frame 13 via a roller pivot 12. A rod 14 is suspended from the pressure frame 13, and a hydraulic cylinder 15 is attached to a lower portion of the rod 14. Hydraulic cylinder 1
5 is generally located at the lower part of the housing 1 and is installed with the pressure side (rod side) upward and the head side downward. Then, by pulling the rod 14 downward by the hydraulic pressure of the hydraulic cylinder 15, a crushing load is finally applied to each crushing roller 3.

[0004] The pulverized raw material 5 supplied from the raw material supply pipe (center chute) 4 to the center of the rotary table 2 moves on the rotary table 2 to the outer periphery of the rotary table 2 by drawing a spiral locus by centrifugal force. Then, it is caught between the crushing race 6 of the rotary table 2 and the crushing roller 3 and crushed. Hot air (primary air) 7 which becomes a part of combustion air is guided through a duct to a lower portion of the housing 1, and the hot air (primary air) 7 is supplied to the turntable 2 and the housing 1.
Blow up through the air throat 8 located between. The pulverized particles are dried while rising inside the housing 1 by hot air (primary air) 7 blowing up from an air throat 8. The granular material transported above the housing 1 falls from the coarse one by gravity (primary classification), and the granular material dropped onto the rotary table 2 is reground by the grinding unit. Further, the slightly fine particles penetrating through the primary classifying section are formed in the housing 1.
Fixed classifier (cyclone separator) installed above
Alternatively, classification is performed again by a rotary classifier (rotary separator) 9. Fine powder smaller than a predetermined particle size that has passed through the classifier is conveyed by airflow as product fine powder 10, and is sent to a burner for pulverized coal combustion in a boiler, for example. Coarse powder larger than a predetermined particle size that has not passed through the classifier falls by gravity onto the rotary table 2 and is pulverized again with the raw material just supplied into the mill. In this way, pulverization is repeated in the mill, and product fine powder satisfying a predetermined particle size is generated.

In the roller mill configured as described above, when the mill is operated with a low load, or when the load is reduced or the mill is stopped, vibration of the mill is a problem. This vibration phenomenon is a kind of frictional vibration caused by slippage between the coal seam and the crushing roller, and is a kind of self-excited vibration as a vibration type. In order to suppress the vibration of the crushing roller, in a conventional technique described in Japanese Utility Model Laid-Open Publication No. 60-35753, a damper device including an accumulator is connected to a passage of pressure oil supplied to a hydraulic cylinder, and the damper device is used. The expansion and contraction of the hydraulic cylinder due to the vibration of the crushing roller is absorbed.

FIG. 6 is a hydraulic circuit diagram showing a roller mill vibration suppressing mechanism described in the above-mentioned publication. In this roller mill, a pair of arms (not shown) supporting a crushing roller are connected via a hydraulic cylinder 20. When one of the crushing rollers is rotated in a direction away from the crushing race of the rotary table, the rotating power is transmitted to the arm of the other crushing roller via the hydraulic cylinder 20, and the crushing is performed. The roller is configured to press against the grinding race. A pipe 22 connected to the hydraulic cylinder 20 is connected to a hydraulic pump P via a damper device 25 having a throttle valve 23 and a check valve 24, and is provided between the hydraulic pump P and the damper device 25. Accumulator 2
6 is connected via a valve 27.

In the roller mill configured as described above, when the hydraulic cylinder 20 is extended by the vibration of the grinding roller,
The pressure oil discharged from the hydraulic cylinder 20 is applied to the damper device 2
5 flows into the accumulator 26 through the throttle valve 23. Conversely, when the hydraulic cylinder 20 contracts due to the vibration of the grinding roller, the volume in the hydraulic cylinder 20 expands,
The pressure oil in the accumulator 26 is drawn into the hydraulic cylinder 20 via the check valve 24. When the pressure oil in the hydraulic cylinder 20 passes through the throttle valve 23, the velocity energy of the pressure oil is reduced by the fluid resistance. Instead of heat, the vibration of the grinding roller is absorbed. Therefore, the movement of the hydraulic cylinder 20 that expands and contracts in accordance with the vertical movement of the grinding roller is suppressed by the function of the damper device 25 inserted into the hydraulic circuit, and vibration of the grinding roller can be prevented.

[0008]

However, in the above-described conventional vibration suppressing mechanism, air may be mixed into the pressurized oil after the hydraulic cylinder 20 or peripheral equipment piping is removed. If the pressure oil contains air, the effect of suppressing the vibration of the crushing roller cannot be sufficiently exhibited. That is, if air is mixed in the pressurized oil, the movement of the hydraulic cylinder 20 which expands and contracts in accordance with the vertical movement of the crushing roller is absorbed by the compression and expansion of the bubbles existing in the pressurized oil, and the damper device 25 Does not perform its original function sufficiently, the inflow and discharge of the pressure oil at the accumulator 26 become insufficient, and the efficiency of converting the speed energy of the pressure oil into heat due to the fluid resistance at the throttle valve 23 decreases. This causes a problem that the vibration of the crushing roller is not sufficiently absorbed.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances of the prior art, and an object of the present invention is to provide a roller mill that can reliably prevent vibration of a crushing roller.

[0010]

SUMMARY OF THE INVENTION According to the present invention, a damper device inserted into a hydraulic circuit of a hydraulic cylinder suppresses vibration of a crushing roller and removes gas mixed in pressurized oil of the hydraulic circuit. A removal device is provided.
According to the roller mill having such a gas removing device, it is possible to easily remove bubbles and dissolved air contained in pressurized oil in the hydraulic cylinder and its piping,
The vibration suppressing effect of the crushing roller by the damper device is not reduced, and the vibration of the crushing roller can be reliably prevented.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A roller mill according to the present invention comprises a plurality of crushing rollers, a rotary table having a groove on the outer peripheral side, and a hydraulic cylinder for urging the crushing roller toward the groove. In a roller mill for crushing a raw material by an interlocking action of the rotary table and the crushing roller rotating while being pressed by the groove, a damper having an accumulator and a throttle valve on at least one of a head side and a rod side of the hydraulic cylinder Connect the device,
Further, a gas removing device for removing gas in the pressurized oil of the hydraulic cylinder is provided.

The hydraulic cylinder is usually provided with one air vent hole on each of the head side and the rod side. However, two air vent holes are provided on one or both of the head side and the rod side. When the gas removal device is connected to the air vent hole via a switching valve, a circulation line that connects the hydraulic cylinder and the gas removal device is formed, and the gas in the pressurized oil can be easily removed.

[0013] Further, in the above structure, the gas removing device is provided with a vacuum pump, a stirrer, and a heater.

[0014]

Embodiments will be described with reference to the drawings.
FIG. 1 is a hydraulic circuit diagram showing a vibration suppression mechanism of a roller mill according to an embodiment of the present invention. The configuration of a roller mill to which this vibration suppression mechanism is applied is the same as that shown in FIG.
That is, the hydraulic cylinder 15 is installed with the cylinder rod 30 side upward and the cylinder head 31 side downward, and a pulverizing load is applied to the pulverizing roller by the hydraulic pressure of the hydraulic cylinder 15.

The hydraulic cylinder 15 is connected to a pressurized oil device 32.
5 is supplied with pressurized oil to the rod side. Although the detailed configuration of the pressurized oil device 32 is not shown in the figure, the pressurized oil device 32 includes a pressurized oil supply pump, a filter, a pressurized oil cooler, and the like. Normally, the pressurized oil supplied to the hydraulic cylinder 15 is 9.
8 × 10 ⁵ Pa to 9.8 × 10 ⁶ Pa (10 kgf / c
m ² to 100 kgf / cm ² ). A damper device 34 is connected to the rod side of the hydraulic cylinder 15 via a valve 33, and the damper device 34 includes a throttle valve 35, an accumulator 36, a pipe 37, and the like. Two air vents 38 and 39 are provided on the rod side of the hydraulic cylinder 15, and a gas removing device 42 is connected to the air vents 38 and 39 via valves 40 and 41, respectively. The gas removing device 42 includes a gas removing tank 43, a vacuum pump 44, a pressurized oil circulation pump 45, piping, and the like.
The pipe 37 of the damper device 34 is connected to the pipe of the gas removing device 42 via valves 46 and 47, respectively. Further, the gas removal tank 43 is provided with a heater 48 for facilitating the circulation of the pressurized oil and a stirrer 49 for facilitating desorption of bubbles and dissolved air in the pressurized oil. . Note that reference numeral 50 in the figure denotes an expansion joint with a coupler.

During operation of the roller mill, a valve 40, which is provided in a pipe connecting the hydraulic cylinder 15 and the gas removing device 42,
Reference numeral 41 is closed, and in this case, pressurized oil is supplied from the pressurized oil device 32 to the rod side of the hydraulic cylinder 15, and a predetermined load is applied to the grinding roller by a pressurized oil device control device (not shown). Pressure is controlled as follows. Further, when the cylinder rod 30 of the hydraulic cylinder 15 expands and contracts due to the vibration of the crushing roller during the operation of the roller mill, the pressurized oil in the rod of the hydraulic cylinder 15 passes through the throttle valve 35 of the damper device 34 to the accumulator 36. Inflow or vice versa, pressurized oil in the accumulator 36
5 and is drawn into the rod of the hydraulic cylinder 15,
The velocity energy is converted into heat by the fluid resistance when the pressurized oil passes through the throttle valve 35, so that the vibration of the grinding roller is suppressed.

If air is mixed in the pressurized oil of the hydraulic cylinder 15 during the operation of the roller mill, the effect of the damper device 34 for suppressing the vibration of the crushing roller is reduced. If there is a possibility that air is mixed in the pressurized oil of the hydraulic cylinder 15, after stopping the operation of the roller mill and closing the valve 33, first, the vacuum pump 43 and the heater 48 of the gas removing device 42 The agitator 49 is started, and the inside of the gas removal tank 43 is kept at a vacuum. In this case, the vacuum pump 43 is rotated by a rotary pump at 1.33 × 10 ² Pa or higher.
While evacuating to 3.99 × 10 ² Pa (1 to 3 Torr), the pressurized oil in the gas removal tank 43 is maintained at about 100 ° C. by the heater 48 and the stirrer 49 to reduce the fluidity of the pressurized oil. Higher (Mineral oil manufactured by Nippon Oil Co., Ltd., which is usually used as pressurized oil for mills (trade name: Highland Wide 4)
The kinematic viscosity of 6) is 80 cSt at 20 ° C. and 8 at 100 ° C.
cSt). Thereafter, the valves 40 and 41 are opened to allow the rod side of the hydraulic cylinder 15 to communicate with the gas removing device 42, and in this state, pressurized oil on the rod side is circulated by the pressurized oil circulation pump 45. By this operation, the air mixed in the pressurized oil on the rod side can be removed in about one hour of operation.

The above operation has been described in connection with the case where the air mixed in the pressurized oil on the rod side of the hydraulic cylinder 15 is removed. Next, the air mixed in the pressurized oil on the pipe 37 side of the damper device 34 is described. The case of removing air will be described. In this case, after the vacuum pump 43 of the gas removing device 42, the heater 48, and the stirrer 49 are started to maintain the inside of the gas removing tank 43 at a vacuum, the valves 40 and 41 communicating with the rod side of the hydraulic cylinder 15 are closed. Instead, the valves 46 and 47 are opened to communicate the pipe 37 on the damper device 34 side with the gas removing device 42. When the pressurized oil on the damper device 34 side is circulated by the pressurized oil circulation pump 45 in this state, the air on the damper device 34 side is removed in the same manner as when air in the pressurized oil on the rod side of the hydraulic cylinder 15 is removed. The air mixed in the pressurized oil can be removed.

FIG. 2 is an explanatory view showing the vibration suppressing effect of the gas removing device 42 provided in the vibration suppressing mechanism of FIG. 1. The vertical axis represents the acceleration of the mill reducer for rotating the turntable at a prescribed speed. The horizontal axis shows the value obtained by dividing the number of revolutions of the rotary classifier used for evaluating roller vibration by the rated number of revolutions. If vibration does not occur even if the rotation speed of the roller mill rotation classifier is increased (acceleration of the reduction gear section is 0.4 G or less), the vibration resistance is high, but if air is not sufficiently vented ( The rotation speed of the classifier before the air bleeding is about 55% lower than that with air bleeding (after the air bleeding). It can be seen that has been reached. This is because the air mixed in the pressurized oil only compressed and expanded, and the vibration energy was not sufficiently absorbed by the throttle valve 35 of the damper device 34.

Normally, as the pressurized oil for the hydraulic cylinder 15, mineral oil, for example, Highland Wide 46 (trade name) of Nippon Oil Co., Ltd. is used. Mineral oils generally have very high air solubility, and as shown in FIG. 3, about 70-80 cc of air per liter of mineral oil at 1 atm.
About 1,200 cc of air is dissolved in 1 liter at 96 × 10 ⁶ Pa (20 kgf / cm ² ). Therefore, removing the air mixed in the pressurized oil using the gas removing device 42 as in the above embodiment is a very effective means for maintaining the roller vibration suppressing function of the roller mill by the damper device 34. It can be said that.

FIG. 4 is a hydraulic circuit diagram showing a vibration suppression mechanism of a roller mill according to another embodiment of the present invention. In this embodiment, the roller mill includes a pressure oil device 32, a rod side of a pressure cylinder 15, and a head. Supply pressurized oil to both sides,
In this method, a crushing load is applied to a crushing roller by a difference between a rod side pressure and a head side pressure. In this case, the hydraulic cylinder 15
A damper device 50 is also connected to the head side of the damper device, and the damper device 50 is connected to the damper device 34 connected to the rod side.
Similarly to the above, it comprises a throttle valve 51, an accumulator 52 and the like. Also, two air vents 53 and 54 are provided on the head side of the hydraulic cylinder 15 similarly to the rod side, and these air vents 53 and 54 are provided with valves 55 and 5 respectively.
6 and connected to a gas removing device 42. The structure and function of the gas removing device 42 are the same as those of the embodiment shown in FIG. 1. When there is a possibility that air is mixed in the pressurized oil of the hydraulic cylinder 15, each valve is appropriately switched. To remove the air mixed in the pressurized oil on the rod side and the head side of the hydraulic cylinder 15 or to remove the damper devices 34 and 5
Air mixed in the pressurized oil on the zero side can be removed.

[0022]

The present invention is embodied in the form described above and has the following effects.

If a damper device inserted into the hydraulic circuit of the hydraulic cylinder suppresses the vibration of the crushing roller and is provided with a gas removing device for removing gas mixed in the pressurized oil of the hydraulic circuit, the inside of the hydraulic cylinder and Bubbles and dissolved air contained in the pressurized oil in the piping of the damper device can be easily removed, and the effect of suppressing the vibration of the crush roller by the damper device can be maintained. The stable operation of the roller mill becomes possible.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram illustrating a vibration suppression mechanism of a roller mill according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a vibration suppressing effect of a gas removing device provided in the vibration suppressing mechanism of FIG.

FIG. 3 is an explanatory diagram showing an amount of air dissolved in pressurized oil.

FIG. 4 is a hydraulic circuit diagram illustrating a vibration suppression mechanism of a roller mill according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a schematic configuration of a general roller mill.

FIG. 6 is a hydraulic circuit diagram showing a roller mill vibration suppressing mechanism according to a conventional example.

[Explanation of symbols]

 15 Hydraulic cylinder 30 Cylinder rod 31 Cylinder head 32 Pressurized oil device 34,50 Damper device 35,51 Throttle valve 36,52 Accumulator 37 Piping 40,41,55,56 Valve 42 Gas removing device 43 Gas removing tank 44 Vacuum pump 45 Pressurized oil circulation pump 48 Heater 49 Stirrer

Continued on the front page (72) Inventor Kazunori Sato 3-36 Takaracho, Kure City, Hiroshima Prefecture Babkotsuk Hitachi Kure Research Institute

Claims (3)

[Claims] 1. A rotary table having a plurality of crushing rollers, a rotary table having a groove on the outer peripheral side, and a hydraulic cylinder for urging and pressing the crushing roller toward the groove, wherein the rotating table and the groove are rotated. In a roller mill that crushes a raw material by an interlocking action of the crushing roller that rotates in a pressed state, a damper device having an accumulator and a throttle valve is connected to at least one of a head side and a rod side of the hydraulic cylinder, and A roller mill comprising a gas removing device for removing gas in pressurized oil of a hydraulic cylinder. 2. The hydraulic cylinder according to claim 1, wherein at least one of a head side and a rod side of the hydraulic cylinder is provided with two air vent holes, and the gas removing device is connected to these air vent holes via a switching valve. Roller mill characterized by the following. 3. The roller mill according to claim 1, wherein the gas removing device includes a vacuum pump, a stirrer, and a heater.